Trump's motivation for the withdrawal is the same as for Obamacare and numerous other things he has done, is doing, or expressed intent to do within his presidential tenure, and it has nothing to do with jobs, the U.S. economy, U.S. national security, or anything else of consequence to Americans. Trump's motivation is purely spite directed against Obama. He is ego-driven and his ego took a bruising when Obama roasted him at that press corps dinner a few years ago. He has since been on a personal mission to "get even" and undo every one of Obama's achievements as president.
Consider that his crusade against Obamacare could jeopardize the health of millions of Americans as they may lose access to affordable health care while the budget to which American health care is tied may redistribute more wealth to the wealthiest, at the expense of those who can least afford it. Likewise, his "pro-coal" energy policy may do more harm to more Americans than it provides jobs, even without considering the broader global implications.
Trump's catchy "Make America great again" slogan and "America first" is just marketing - not a promise or a goal, but something he can pitch to build the required support for his true purpose. Any of his other initiatives tangential to his anti-Obama crusade - the Mexican wall and travel ban, for example, is just pandering to his base to hold on to the necessary support to facilitate his real objective.
He may initially have sought the presidency for other reasons - a competitive individual in search of his next ego boost. He may initially have had no real idea what to do with the job if he gets it, other than self or family enrichment, but Obama furnished him with an agenda.
Trump will use jobs, the economy, or security as justification, but when you look more closely, it's just rationalization - cherry-picking reports and news articles which appear to favor his actions whether or not they are true, accurate, or even relevant. None of it is motivating him, only providing him with arguments he can trot out as he systematically undoes as much of what Obama accomplished as he can. The true motivation is, in a word, vendetta.